Not really, most of us would be surprised if anything on the plate is correct. The ideal, well the base line is 10% of ATM but that is just a figure folks use, when you have all your junk inside being 20 kg either side is okay, if your van is 2t then 180 to 210 kg probably......Big Mal loaded up is roughly around the 2.6t had a 225kg ball but adding an extra battery moved it to 245kg, add some more if I fill both tanks.... a good test for checking weight movement is jerry cans of water placed in various spots to simulate loading, 20lts/20kg... works well no mess or stuffing around....those ball weight devices need to be set up just right to get a near correct figure, they can be wrong very easily.
On the plate ignore the tare weight it will be wrong the figures that you need to comply with is the ATM (total van weight wheels and jockey) GTM ( weight on the wheels) if when hooked up the GTM of van and GVM of tug is more than the GCM of tug then you are in trouble (POO) ....

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